Fundamental and Higher-Mode Density-Wave Oscillations in Two-Phase Flow

1972 ◽  
Vol 94 (2) ◽  
pp. 189-195 ◽  
Author(s):  
G. Yadigaroglu ◽  
A. E. Bergles
Keyword(s):  
Heat Capacity ◽  
Atmospheric Pressure ◽  
Single Phase ◽  
Two Phase Flow ◽  
Density Wave ◽  
Phase Region ◽  
Flow Instabilities ◽  
Phase Flow ◽  
Two Phase ◽  
Density Wave Oscillations

This paper treats the oscillatory two-phase flow instabilities commonly referred to as density-wave oscillations. A dynamic analysis of the single-phase region of a boiling channel, accounting for wall heat capacity and the effect of pressure variations on the movements of the boiling boundary, is summarized. Experiments conducted with a Freon-113 channel at atmospheric pressure revealed the existence of “higher-mode” oscillations. These appeared at high subcoolings and low power levels and were characterized by unexpectedly short periods that were fractions of the transit time. The presence of the higher modes and other observations are explained in terms of the dynamic behavior of the boiling boundary.

COMPARISON OF THE EFFECTS OF DIFFERENT TYPES OF TUBE INSERTS ON TWO-PHASE FLOW INSTABILITIES

2013 ◽  
Vol 20 (2) ◽  
pp. 179-194 ◽  
Author(s):  
Gokhan Omeroglu ◽  
Omer Gomakh ◽  
Sendogan Karagoz ◽  
Suleyman Karsli
Keyword(s):  
Two Phase Flow ◽  
Flow Instabilities ◽  
Phase Flow ◽  
Two Phase ◽  
Different Types

TWO-PHASE FLOW INSTABILITIES ANALYSES IN BOILING WATER REACTOR

2016 ◽  
Author(s):  
Antonella Lombardi Costa ◽  
WILMER ARUQUIPA COLOMA ◽  
Antonella Lombardi Costa ◽  
Claubia Pereira ◽  
Maria Veloso ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Boiling Water ◽  
Flow Instabilities ◽  
Boiling Water Reactor ◽  
Phase Flow ◽  
Two Phase ◽  
Water Reactor

Effect of heat transfer augmentation on two-phase flow instabilities in a vertical boiling channel

1983 ◽  
Vol 17 (3) ◽  
pp. 161-169 ◽  
Author(s):  
A. Mentes ◽  
O. T. Yildirim ◽  
H. Gürgenci ◽  
S. Kakaç ◽  
T. N. Veziro¯glu
Keyword(s):  
Heat Transfer ◽  
Two Phase Flow ◽  
Flow Instabilities ◽  
Phase Flow ◽  
Two Phase ◽  
Heat Transfer Augmentation

Research on Two-Phase Flow Instability in Evaporator of Refrigeration System

2010 ◽  
Author(s):  
Nan Liang ◽  
Changqing Tian ◽  
Shuangquan Shao
Keyword(s):  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Two Phase Flow ◽  
Density Wave ◽  
Phase Flow ◽  
Constant Mass ◽  
Refrigeration System ◽  
Two Phase

As one kind of fluid machinery related to the two-phase flow, the refrigeration system encounters more problems of instability. It is essential to ensure the stability of the refrigeration systems for the operation and efficiency. This paper presents the experimental investigation on the static and dynamic instability in an evaporator of refrigeration system. The static instability experiments showed that the oscillatory period and swing of the mixture-vapor transition point by observation with a camera through the transparent quartz glass tube at the outlet of the evaporator. The pressure drop versus mass flow rate curves of refrigerant two phase flow in the evaporator were obtained with a negative slope region in addition to two positive slope regions, thus making the flow rate a multi-valued function of the pressure drop. For dynamic instabilities in the evaporation process, three types of oscillations (density wave type, pressure drop type and thermal type) were observed at different mass flow rates and heat fluxes, which can be represented in the pressure drop versus mass flow rate curves. For the dynamic instabilities, density wave oscillations happen when the heat flux is high with the constant mass flow rate. Thermal oscillations happen when the heat flux is correspondingly low with constant mass flow rate. Though the refrigeration system do not have special tank, the accumulator and receiver provide enough compressible volume to induce the pressure drop oscillations. The representation and characteristic of each oscillation type were also analyzed in the paper.

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